Metastatic bone disease involves tumor-induced skeletal metastases which commonly result from breast cancer, prostate cancer, lung cancer, renal cancer, thyroid cancer and multiple myeloma. The prevalence of bone metastases in patients with these cancers may be as high as 60-85%. Patients with these diseases that have bone dominant or bone only metastases frequently have prolonged survival, usually associated with clinical morbidity. The most frequent clinical manifestations of bone metastases are pain, pathological fracture, immobility, nerve root or spinal cord compression, hypercalcemia and compromised hematopoiesis. The scope of metastatic bone disease is highlighted by the fact that on any given day, approximately 4 million people worldwide suffer from cancer pain and that at least 40-50% of all cancer pain is due to skeletal metastases.
Hypercalcemia of malignancy is also tumor-induced. It is characterized by high levels of serum calcium and is often associated with metastatic bone disease, particularly with non-ambulatory patients. It is estimated that hypercalcemia develops in 5% to 10% of hospital cancer patients. Symptoms of hypercalcemia include fatigue, malaise, anorexia, polydipsia, nausea, constipation, muscle weakness, apathy, obtundation and even coma. These metabolic complications of malignancy mostly reflect a disseminated disease. Thus, in the majority of cases, malignancy is recognized before the appearance of hypercalcemia. However, in rare situations, such as neuroendocrine tumors, hypercalcemia may run a slowly developing course and even precede the discovery of the tumor.
The category of metabolic bone disease includes osteoporosis and Paget's disease, in which osteoporosis is one of the most important disorders associated with aging. More than 1.5 million Americans have fractures related to osteoporosis each year, with attendant pain, deformity and loss of independence. The annual cost to the U.S. health care system is at least $10 billion. Because of the aging of the population and increases over time in the incidence of fractures, these already huge costs will more than double over the next 30 years unless a comprehensive program of prevention and treatment is initiated soon. The most important preventable cause of fractures is low bone mass. During the course of their lifetimes, women lose about 50 percent of their cancellous bone and 30 percent of their cortical bone, and men lose about 30 percent and 20 percent, respectively. Cancellous bone is concentrated in the spinal column and at the ends of long bones; these areas are the main sites of osteoporotic fractures. The tendency of the elderly to fall, however, is an important independent cause of fractures. Although little can be done at present to prevent such falls, important advances have been made in methods of retarding bone loss involving the use of bisphosphonates.
Alendronate, 4-amino-1-hydroxybutylidene-1,1-bisphosphonic acid monosodium trihydrate, is a new bisphosphonate agent for combatting bone resorption in metabolic bone diseases including osteoporosis and Paget's disease and is described as a composition, method of use and synthesis along with other pharmaceutically acceptable salts in U.S. Pat. Nos. 4,922,007 and 5,019,651 (both assigned to Merck).
Alendronate is also used in treating metastatic bone disease for example, as described in Cancer 72, (Supplement) 3443-3452(1993) by S. D. Averbuch. Its use in treating hypercalcemia of malignancy is described in Journal of Clinical Oncology, Vol. 11, No 8 (August), 1993, pp. 1618-1623 by S. R. Nussbaum et al.
Alendronate currently is administered orally or intravenously to patients. The advantage of intravenous therapy over oral dosage therapy is that therapeutically higher levels of serum alendronate can be achieved in a relatively short time period. This is especially important in hypercalcemia of malignancy where it is desired to lower serum calcium levels as quickly as possible to minimize calcium deposition and resulting bone disorders.
However, a major problem is that intravenous solutions of alendronate are prepared and packaged in glass containers and tend to form a precipitate during shelf storage. This has shown to be a result of metal ion precipitation of alendronate at increasingly higher pH values forming insoluble metal complexes. Precipitates are very dangerous in an intravenous formulation since they can lead to embolisms and blocking of capillaries which can be fatal. Thus, intravenous formulations for clinical studies and marketing must pass a series of rigid government (United States or international) and compendial tests, including the USP (United States Pharmacopeia in the United States) test for particulate matter. With respect to packaging, the use of glass containers is highly desirable since the formulation contents can be quickly inspected for the presence of particulates, and glass is a very efficient and convenient medium for packaging.
What is desired is a therapeutically effective alendronate intravenous formulation which is solution stable, isotonic with human blood, can be packaged in glass, meets government and compendial (USP in the US) particulate standards, and which can be used as effective therapy to optimally treat patients with metastatic bone disease, hypercalcemia of malignancy and/or metabolic bone disease.